It is well known in the field of law enforcement to use fingerprints for identification of suspects. Early on, fingerprints were located by dusting, a process in which a commercially prepared fingerprint powder consisting mainly of carbon black and fluorescent powder carried on plant spores and adhered to the moisture left by a print on a surface. After the prints were dusted, the prints were lifted using a transparent tape, such as Scotch.RTM. transparent tape. The system suffered several drawbacks, including that prints were frequently overlooked, that the print could easily be destroyed by improper handling and that the lifted print was not easily usable in later identification procedures.
Subsequently, there developed the process of developing prints by placing a piece of evidence in a container, such as an aquarium, with a small amount of cyanoacrylate ester, which was heated so that it would fume. A useful form of cyanoacrylate ester is commonly available as the principal ingredient in Super Glue.RTM.. As the ester was boiled, the chamber filled with fumes, and the fumes reacted with moisture retained in the print to create a polymer. This polymer made a hard representation of the print. The problems with this procedure are that the cyanoacrylate ester had to be heated, producing a dense, white smoke. The large quantity of fumes are irritating to the eyes and respiratory system of the operator when opening the chamber. Furthermore, the possibility existed that an operator wearing contact lenses could have the contact lenses adhere to the eyes if exposed to the dense fumes. These fumes are reactive with moisture and, thus, excess moisture on the piece of evidence could react with the fumes and obliterate the print.
More recently there has been an improvement in the cyanoacrylate ester method whereby evidence is placed in a vacuum chamber, the pressure is reduced in the vacuum chamber, and with a slight amount of heat, the glue is boiled and the print will develop. Such a chamber is sold by Payton Scientific, Inc. under the trade name Cyvac. The Cyvac chamber utilizes two pumps and a series of values. The Cyvac chamber has the disadvantages of complex construction, poor circulation of fumes within the chamber, and the possibility of operator error. In addition, the Cyvac device is quite expensive.
Thus, there has been a need in the art to provide a vacuum chamber of simple construction, with minimum parts, with circulation which assures good print development, and a mechanism to prevent destruction of prints by operator error and at the same time be economical.